gen test3

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Most TNRE repeats involve expansion of which codon? GAA CAG Any codon containing three of the same bases CCC ATG

CAG

Spontaneous mutations include: Depurination, deamination, errors in DNA replication UV light, deamination, depurination, errors in DNA replication UV light, radiation, deamination, depurination UV light, radiation, errors in replication, deamination

Depurination, deamination, errors in DNA replication

A wholphin is a rare hybrid animal born from mating a female bottlenose dolphin with a male false killer whale. Wholphins are diploid, and interestingly are fertile. What can you conclude from the fact that wholphins are fertile? Dolphins and false killer whales likely have the same number of chromosomes One of the parents must have been aneuploid Wholphins are allotetraploid Dolphins and false killer whales are actually the same species

Dolphins and false killer whales likely have the same number of chromosomes

Q1. A short genetic sequence, which may be recognized by DNA primase, is repeated many times throughout the E. coli chromosome. Researchers have hypothesized that DNA primase may recognize this sequence as a site to begin the synthesis of an RNA primer for DNA replication. The E. coli chromosome is roughly 4.6 million bp in length. How many copies of the DNA primase recognition sequence would be necessary to replicate the entire E. coli chromosome?

For making Okasaki fragments a primer is needed. The length of Okasaki fragments is considered to range from 1000 - 2000 bp. If we assume the average length of an Okasaki fragment as 1500 bp, the number of primase recognition sequences for a bacterial genome of 4.6x10^6 bp size = 4.6x10^6/1500 = 3066.67 or 3067 copies.

Telomeric sequences are typically: CG rich AG rich GT rich AT rich

GT rich

One way that bacterial cells regulate DNA replication is by GATC methylation sites within the origin of replication. Would this mechanism work if the DNA was conservatively (rather than semiconservatively) replicated? Why or why not?

This would not work in conservative replication. In conservative replication, one of the double helices would always be completely methylated, and the other would not. Therefore, the cell would not be able to delay the next round of DNA replication by controlling the methylation of DNA strands.

Which of the following processes accounts for the tremendous variation in antibody structure? RNA editing integrase activity physiological adaptation site-specific recombination hot spots of mutation in the immunoglobin genes

site-specific recombination

The common goldfish Carrassius auratushas 100 chromosomes and is tetraploid. The goldfish therefore has___ sets of chromosomes containing ____chromosomes each. 2; 50 4; 25 4; 100 1; 100

4; 25

A temporary change in the conformation of a nitrogenous base is called: Dupurination A tautomeric shift Deamination None of these answers are correct

A tautomeric shift

Q3. The compound known as nitrous acid is a reactive chemical that replaces amino groups (NH2) with keto groups (=O). When nitrous acid reacts with the bases in DNA, it can change cytosine to uracil and adenine to hypoxanthine. A DNA double helix has the following sequence: TTGGATGCTGG AACCTACGACC A. What would be the sequence of this double helix immediately after reaction with nitrous acid? Let the letter H represent hypoxanthine and U represent uracil. B. After the nitrous acid is removed, suppose this DNA was replicated for two generations. Illustrate the sequences of the DNA products after each replication. Note: During replication, uracil hydrogen bonds with adenine, and hypoxanthine hydrogen bonds with cytosine.

A. TTGGHTGUTGG HHUUTHUGHUU B. TTGGHTGUTGG HHUUTHUGHUU . TTGGHTGUTGG CCAAACACCAA AACCCACAACC HHUUTHUGHUU TTGGHTGUTGG TTGGGTGTTGG CCAAACACCAA CCAAACACCAA AACCCACAACC AACCCACAACC GGTTTGTGGTT HHUUTHUGHUU

A mutagen is: A depurinated base An agent that can alter the structure of DNA and cause mutations A DNA polymerase without a 5' to 3' exonuclease A deaminated base

An agent that can alter the structure of DNA and cause mutations

What is an allodiploid? What factor determines the fertility of an allodiploid? Why are allotetraploids more likely than allodiploids to be fertile?

An allodiploid is an organism having one set of chromosomes from two different species. Unless the two species are closely related evolutionarily, the chromosomes do not synapse during meiosis. Therefore, they do not segregate properly, which produces aneuploid gametes that are usually inviable. By comparison, allotetraploids that have two sets of chromosomes from each species are more likely to be fertile because each chromosome has a homolog to pair with during meiosis.

An example of a suppressor mutation would be: An intergenic mutation that activates a transcription factor that increases the expression of a normal protein An intragenic mutation that restores the inactive protein's structure A mutation that suppresses cell growth An intergenic mutation that increases the activity of a protein performing a different function as the mutated protein

An intragenic mutation that restores the inactive protein's structure

Q3.Male honeybees, which are monoploid, produce sperm by meiosis. Explain what unusual event (compared to other animals) must occur during spermatogenesis in honeybees to produce sperm? Does this unusual event occur during meiosis I or meiosis II?

Complete nondisjunction occurs during meiosis I. One nucleus receives all the chromosomes and the other nucleus does not get any. The nucleus without any chromosomes will die off. The nucleus with all the chromosomes will proceeds through a normal meiosis II to produce two haploid sperm cells.

Mutations that change the configuration of a protein at a specific temperature are called ___ mutations. Neutral Conditional Deleterious Beneficial

Conditional

Which of the following domain types is unique to the heavy chain of an immunoglobin polypeptide? C V J D

D

Which of the following attaches adjacent Okazaki fragments, forming a continuous DNA strand: DNA Polymerase III Topoisomerase DNA primase DNA ligase DNA Polymerase I

DNA ligase

Which of the following may account for the process of gene conversion? nucleotide excision repair DNA mismatch repair retrotransposition photolyase activity

DNA mismatch repair

Synthesizes the lagging strand of the DNA. DNA primase DNA polymerase I DNA polymerase III Topoisomerase DNA ligase

DNA polymerase III

Which of the following fills in small regions of DNA where the RNA primers were located? DNA polymerase III DNA helicase DNA ligase DNA primase DNA polymerase I

DNA polymerase III

The conversion of cytosine to uracil in DNA is an example of: Depurination Deamination Demethylation Tautomeric shifts

Deamination

Dam methylase (DNA adenine methyl transferase) recognizes which of the following sequences: CATG GATC GTAC CAAG

GATC

Which repair mechanism utilizes MutL, MutH, and MutS proteins in E. coli? Base excision repair Nonhomologous end joining (NHEJ) Direct repair Mismatch pair Nucleotide excision repair

Mismatch pair

Describe three naturally occurring ways that chromosome number can change.

Nondisjunction is a mechanism whereby the chromosomes do not segregate equally into the two daughter cells. This can occur during meiosis (#1) to produce cells with altered numbers of chromosomes, or it can occur during mitosis (#2) to produce an individual with genetic mosaicism. A third way to alter chromosome number (#3) is by an interspecies cross that produces an alloploid.

Which types of mutations are least likely to be subjected to natural selection? Nonsense Missense Insertion Silent

Silent

3' ends of the eukaryotic linear chromosomes are replicated by: DNA polymerase a Primase DNA polymerase b DNA polymerase I Telomerase

Telomerase

How does position effect influence gene expression? Translocations always result in a gene being recombined into an area of heterochromatin Translocations may result in a promoter that is normally used for one gene now controlling an entirely different gene Since this mechanism relies on recombination it relies on the positioning of one allele so that it is under the control of the other allele. Point mutations in promoters frequently occur by this mechanism

Translocations may result in a promoter that is normally used for one gene now controlling an entirely different gene

Which of the following stops the replication of DNA in prokaryotes? Okazaki fragments Tus proteins the end of the chromosome DNA ligase

Tus proteins

All light chain polypeptides in an immunoglobin contain which of the following? a C region a V region a J region only a C and a V region all of the above

all of the above

What term describes an organism with two complete sets of chromosomes from two different species? allotetraploid aneuploid tetrapoid allodiploid

allotetraploid

Okazaki fragments do which of the following? assist in the synthesis of DNA from the lagging strand assist in forming the replication fork reform the double helix following replication bind to the oriC region

assist in the synthesis of DNA from the lagging strand

Humans with aneuploidy who survive usually have incorrect numbers of chromosome 13, 18, 21, or the sex chromosomes. This may be due to: the chromosomes have clusters of genes that aid in embryonic growth the chromosomes are small and carry relatively few genes X-chromosome inactivation both b and c may be correct

both b and c may be correct

The term endopolyploidy refers to the phenomenon of having: extra sets of chromosomes in gametes extra chromosomes in the cell nucleus too many chromosomes certain cells of the body with extra sets of chromosomes

certain cells of the body with extra sets of chromosomes

A drug that is used to experimentally produce polyploidy in organisms is: colchicine karyocine polymosca doxorubicin penicillin

colchicine

Which of the following most likely accounts for the majority of the recombination events during both DNA repair and meiosis? a nick in only one strand of the DNA DNA gap repair synthesis heteroduplex formation double-stranded breaks in DNA

double-stranded breaks in DNA

If eukaryotic cells evolved such that lagging strand DNA synthesis could occur continuously (without the use of Okazaki fragments), what enzyme would likely no longer be needed for DNA replication? topoisomerase primase flap endonuclease helicase

flap endonuclease

Gene conversion requires recombination and which of the following events? excision repair inversion reversion heteroduplex formation suppression

heteroduplex formation

Which human cells exhibit endopolyploidy? red blood cells sex cells nerve cells all somatic cells liver cells

liver cells

The polytene chromosomes of Drosophilaare an example of: inversion loops aneuploidy polyploidy translocations none of these answers are correct

polyploidy

Which of the following best describes the function of the RecA protein in E. coli recombination? is involved in the initial formation of the Holliday junctions promotes strand invasion and formation of the D loop resolves Holliday junctions into separate chromosomes recognizes double-stranded breaks in the DNA

promotes strand invasion and formation of the D loop

The process of ___ is extremely important in generating genetic diversity. translation replication transcription recombination

recombination

The Holliday model is used to explain which of the following: recombination between homologous chromosomes the migration of transposons recombination between sister chromatids the generation of antibody diversity

recombination between homologous chromosomes

Which of the following often leads to deletion in chromosome sequences? the creation of harlequin chromosomes recombination between sister chromatids the action of transposons recombination between homologous chromosomes

recombination between homologous chromosomes

Meiotic nondisjunction usually occurs during meiosis I. What is not separating properly: bivalents or sister chromatids? What is not separating properly during mitotic nondisjunction? In meiotic nondisjunction, the bivalents are not

separating correctly during meiosis I. During mitotic nondisjunction, the sister chromatids are not separating properly.

Which of the following is NOT correct concerning the initiation of bacterial replication? Topoisomerase II moves ahead of the replication fork to remove supercoils the strands are initially separated at GC-rich regions of DNA it involves a region o DNA called oriC DNA proteins bind to the DNA to begin separation of the strands

the strands are initially separated at GC-rich regions of DNA

What type of plants are usually seedless? tetraploid triploid diploid aneuploid

triploid

The somatic cells of an allotetraploid contain: one set of chromosomes from four different species one set of chromosomes from two different species four sets of chromosomes from one species two sets of chromosomes from two different species

two sets of chromosomes from two different species


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